Merge pull request #1472 from pybamm-team/issue-1465-evaluate-function-parameters

#1465 allow evaluate parameter to return arrays

Author: rtimms

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## Features
 
+-   `plot` and `plot2D` now take and return a matplotlib Axis to allow for easier customization ([#1472](https://github.com/pybamm-team/PyBaMM/pull/1472))
+-   `ParameterValues.evaluate` can now return arrays to allow function parameters to be easily evaluated ([#1472](https://github.com/pybamm-team/PyBaMM/pull/1472))
 -   Added Batch Study class ([#1455](https://github.com/pybamm-team/PyBaMM/pull/1455))
 -   Added `ConcatenationVariable`, which is automatically created when variables are concatenated ([#1453](https://github.com/pybamm-team/PyBaMM/pull/1453))
 -   Added "fast with events" mode for the CasADi solver, which solves a model and finds events more efficiently than "safe" mode. As of PR #1450 this feature is still being tested and "safe" mode remains the default ([#1450](https://github.com/pybamm-team/PyBaMM/pull/1450))

pybamm/parameters/parameter_values.py

@@ -776,14 +776,14 @@ def evaluate(self, symbol):
 
         Returns
         -------
-        number of array
+        number or array
             The evaluated symbol
         """
         processed_symbol = self.process_symbol(symbol)
-        if processed_symbol.evaluates_to_constant_number():
+        if processed_symbol.is_constant():
             return processed_symbol.evaluate()
         else:
-            raise ValueError("symbol must evaluate to a constant scalar")
+            raise ValueError("symbol must evaluate to a constant scalar or array")
 
     def _ipython_key_completions_(self):
         return list(self._dict_items.keys())

pybamm/plotting/plot.py

@@ -5,7 +5,7 @@
 from .quick_plot import ax_min, ax_max
 
 
-def plot(x, y, xlabel=None, ylabel=None, title=None, testing=False, **kwargs):
+def plot(x, y, ax=None, testing=False, **kwargs):
     """
     Generate a simple 1D plot. Calls `matplotlib.pyplot.plot` with keyword
     arguments 'kwargs'. For a list of 'kwargs' see the
@@ -17,10 +17,8 @@ def plot(x, y, xlabel=None, ylabel=None, title=None, testing=False, **kwargs):
         The array to plot on the x axis
     y : :class:`pybamm.Array`
         The array to plot on the y axis
-    xlabel : str, optional
-        The label for the x axis
-    ylabel : str, optional
-        The label for the y axis
+    ax : matplotlib Axis, optional
+        The axis on which to put the plot. If None, a new figure and axis is created.
     testing : bool, optional
         Whether to actually make the plot (turned off for unit tests)
     kwargs
@@ -34,13 +32,15 @@ def plot(x, y, xlabel=None, ylabel=None, title=None, testing=False, **kwargs):
     if not isinstance(y, pybamm.Array):
         raise TypeError("y must be 'pybamm.Array'")
 
-    plt.plot(x.entries, y.entries, **kwargs)
-    plt.ylim([ax_min(y.entries), ax_max(y.entries)])
-    plt.xlabel(xlabel)
-    plt.ylabel(ylabel)
-    plt.title(title)
+    if ax is not None:
+        testing = True
+    else:
+        _, ax = plt.subplots()
+
+    ax.plot(x.entries, y.entries, **kwargs)
+    ax.set_ylim([ax_min(y.entries), ax_max(y.entries)])
 
     if not testing:  # pragma: no cover
         plt.show()
 
-    return
+    return ax

pybamm/plotting/plot2D.py

@@ -5,7 +5,7 @@
 from .quick_plot import ax_min, ax_max
 
 
-def plot2D(x, y, z, xlabel=None, ylabel=None, title=None, testing=False, **kwargs):
+def plot2D(x, y, z, ax=None, testing=False, **kwargs):
     """
     Generate a simple 2D plot. Calls `matplotlib.pyplot.contourf` with keyword
     arguments 'kwargs'.  For a list of 'kwargs' see the
@@ -19,12 +19,8 @@ def plot2D(x, y, z, xlabel=None, ylabel=None, title=None, testing=False, **kwarg
         The array to plot on the y axis. Can be of shape (M, N)  or (M, 1)
     z : :class:`pybamm.Array`
         The array to plot on the z axis. Is of shape (M, N)
-    xlabel : str, optional
-        The label for the x axis
-    ylabel : str, optional
-        The label for the y axis
-    title : str, optional
-        The title for the plot
+    ax : matplotlib Axis, optional
+        The axis on which to put the plot. If None, a new figure and axis is created.
     testing : bool, optional
         Whether to actually make the plot (turned off for unit tests)
 
@@ -38,6 +34,11 @@ def plot2D(x, y, z, xlabel=None, ylabel=None, title=None, testing=False, **kwarg
     if not isinstance(z, pybamm.Array):
         raise TypeError("z must be 'pybamm.Array'")
 
+    if ax is not None:
+        testing = True
+    else:
+        _, ax = plt.subplots()
+
     # Get correct entries of x and y depending on shape
     if x.shape == y.shape == z.shape:
         x_entries = x.entries
@@ -46,20 +47,17 @@ def plot2D(x, y, z, xlabel=None, ylabel=None, title=None, testing=False, **kwarg
         x_entries = x.entries[:, 0]
         y_entries = y.entries[:, 0]
 
-    plt.contourf(
+    plot = ax.contourf(
         x_entries,
         y_entries,
         z.entries,
         vmin=ax_min(z.entries),
         vmax=ax_max(z.entries),
         **kwargs
     )
-    plt.xlabel(xlabel)
-    plt.ylabel(ylabel)
-    plt.title(title)
-    plt.colorbar()
+    plt.colorbar(plot, ax=ax)
 
     if not testing:  # pragma: no cover
         plt.show()
 
-    return
+    return ax

tests/unit/test_parameters/test_parameter_values.py

@@ -756,13 +756,14 @@ def test_evaluate(self):
         c = pybamm.Parameter("c")
         self.assertEqual(parameter_values.evaluate(a), 1)
         self.assertEqual(parameter_values.evaluate(a + (b * c)), 7)
+        d = pybamm.Parameter("a") + pybamm.Parameter("b") * pybamm.Array([4, 5])
+        np.testing.assert_array_equal(
+            parameter_values.evaluate(d), np.array([9, 11])[:, np.newaxis]
+        )
 
         y = pybamm.StateVector(slice(0, 1))
         with self.assertRaises(ValueError):
             parameter_values.evaluate(y)
-        array = pybamm.Array(np.array([1, 2, 3]))
-        with self.assertRaises(ValueError):
-            parameter_values.evaluate(array)
 
     def test_export_csv(self):
         def some_function(self):

tests/unit/test_plotting/test_plot.py

@@ -1,13 +1,18 @@
 import pybamm
 import unittest
 import numpy as np
+import matplotlib.pyplot as plt
 
 
 class TestPlot(unittest.TestCase):
     def test_plot(self):
         x = pybamm.Array(np.array([0, 3, 10]))
         y = pybamm.Array(np.array([6, 16, 78]))
-        pybamm.plot(x, y, xlabel="x", ylabel="y", title="title", testing=True)
+        pybamm.plot(x, y, testing=True)
+
+        _, ax = plt.subplots()
+        ax_out = pybamm.plot(x, y, ax=ax, testing=True)
+        self.assertEqual(ax_out, ax)
 
     def test_plot_fail(self):
         x = pybamm.Array(np.array([0]))
@@ -22,10 +27,14 @@ def test_plot2D(self):
         X, Y = pybamm.meshgrid(x, y)
 
         # plot with array directly
-        pybamm.plot2D(x, y, Y, xlabel="x", ylabel="y", title="title", testing=True)
+        pybamm.plot2D(x, y, Y, testing=True)
 
         # plot with meshgrid
-        pybamm.plot2D(X, Y, Y, xlabel="x", ylabel="y", title="title", testing=True)
+        pybamm.plot2D(X, Y, Y, testing=True)
+
+        _, ax = plt.subplots()
+        ax_out = pybamm.plot2D(X, Y, Y, ax=ax, testing=True)
+        self.assertEqual(ax_out, ax)
 
     def test_plot2D_fail(self):
         x = pybamm.Array(np.array([0]))